1 Serviço de Cirurgia Digestiva Hospital de Clínicas de Porto Alegre Ramiro Barcelos, Porto Alegre RS, Brazil Address correspondence to: Cleber Rosito Pinto Kruel Capes, Ph.D., Post-doctoral Research Program Rua Ramiro Barcelos, 2350 Sala 600, CEP 90035-003 - Porto Alegre, Brazil.